Q. How to spot the symptoms of high blood sugar?

Answered by
Dr. Prabhakar Laxman Jathar
and medically reviewed by iCliniq medical review team.
Published on Nov 11, 2019

Hello doctor,

How to spot symptoms of high blood sugar and warning signs for high blood sugar and pre-diabetes? I would like to know at least one symptom of hyperglycemia, and explanation of why that symptom occurs during a bout of high blood sugar?

Dr. Prabhakar Laxman Jathar

Diabetology General Practitioner


Welcome to icliniq.com.

Usually high blood glucose (hyperglycemia) symptoms are not very obvious, hence people do not come to know about the problem easily.

So called typical symptoms of diabetes or hyperglycemia are : excess thirst (polydypsia), excess hunger (polyphagia) and excess urination (polyuria) are not easily recognizable. When diabetes begins patients tend to have more thirst, more hunger and more passing of urine specially at night, disturbing the sleep. In addition persons tend to have unexplained weight loss (due loss of excess glucose through urine) and unexplained perpetual tiredness.

Our kidneys normally absorb all the glucose filtered, no glucose is excreted in the urine in a normal person. But if blood glucose increases beyond 180 mg/ 100 ml, then the kidneys are unable to retain the same, hence in hyperglycemia all the excess glucose is sent in the urine. In the urinary bladder when more glucose is present due to osmosis it draws more water and patient get repeated urge to pass urine. Excess passage of urine leads to more or increased thirst, hence dryness of mouth. To combat that person tends to drink more water. Loss of glucose indirectly leads to energy loss, tiredness, weight loss, fatigue and even the increased hunger.

Prediabetes is a condition when blood glucose levels are above normal but below the diagnostic limit. That is fasting glucose between 101 to 125 mg/ 100 ml and post-prandial glucose between 141 to 199 mg/100 ml and HbA1c% between 5.7 % to 6.4%.

Diabetes is diagnosed when fasting glucose is 126 mg/dL and above, post-prandial glucose is 200 mg/dL and above, and HbA1c% is 6.5 % and above. Unfortunately there are no very specific symptoms that can be attributed to hyperglycemia which can be easily recognizable. Hence more that 46% of people with diabetes do not come to know that they have the disease. Most often it is a chance diagnosis.

I hope this helps.

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